Photochemotherapeutic method using 5-aminolevulinic acid and other precursors of endogenous porphyrins

ABSTRACT

Methods of detecting and treating rapidly growing exogenous cells, such as Protista, or parasites, that preferentially accumulate a photoactivatable porphyrin in which 5-aminolevulinic acid or precursor thereof is administered to the patient, or contacted to the exogenous cells, in an amount sufficient to induce synthesis fluorescence and/or photosensitizing concentrations of a protoporphyrin IX in the exogenous cells, followed by exposure of the exogenous cells to light of photoactivating wavelengths.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a Divisional Application of application Ser. No.09/816,329, filed Mar. 26, 2001, which is a Continuation Application ofapplication Ser. No. 09/293,835, filed Apr. 19, 1999, which is in turn aContinuation-in-part of application Ser. No. 08/082,113 (now U.S. Pat.No. 5,422,093), filed Jun. 28, 1993, which is in turn aContinuation-in-part of application Ser. No. 07/865,151 (now U.S. Pat.No. 5,234,940), filed Apr. 8, 1992, which is in turn aContinuation-in-part of application Ser. No. 07/783,750 (now U.S. Pat.No. 5,211,938), filed Oct. 28, 1991, which is in turn a Continuation ofapplication Ser. No. 07/386,414 (now U.S. Pat. No. 5,079,262), filedJul. 28, 1989.

FIELD OF INVENTION

[0002] This invention relates to the detection and treatment, by inducedfluorescence and photochemotherapy, respectively, of certain tissueabnormalities (both cancerous and non-malignant of endogenous andexogenous origin), hyperproliferative cells, and normal cells. Theinvention also relates to the detection and treatment of abnormalitiesin body fluids or suspensions of tissues containing abnormal cells byinduced fluorescence and photochemotherapy.

BACKGROUND OF INVENTION

[0003] Tissue abnormalities involving the skin usually are detected andassessed by a combination of visual inspection and palpation. In certainclinical situations the sensitivity of the visual inspection can beenhanced by the use of non-white light (either ultraviolet or a narrowband in the visible), or by the prior application of acontrast-enhancing agent such as dilute acetic acid or certain stains.Tissues abnormalities that involve surfaces that cannot be palpated(such as the bronchi or the urinary bladder) may be visualized via anappropriate scope. Some specialized scopes can detect inducedfluorescence. If the abnormality in question is associated with adifference in either the extent or the pattern of tissuevascularization, such a scope may be used to determine the limits of thearea involved by the abnormality, by visualizing an injected bolus offluorescein or other fluorescent material as it passes through thevasculature of both the lesion and the adjacent normal tissue.

[0004] In addition, fluorescence-detecting scopes are being usedexperimentally to identify areas of tissue that show strong porphyrinfluorescence following the intravenous injection of exogenous porphyrinssuch as hematophorphyrin IX (HpIX), hematoporphyrin derivative (HpD), or“dihematoporphyrin ether”. Such porphyrins tend to accumulatesemi-preferentially in malignant tissues, but they also accumulate intissues that are regenerating following an injury or in the rapidlygrowing tissues of an embryo or fetus. Normal liver, spleen, and kidneyalso tend to accumulate these porphyrins. Using such compounds andfluorescence-detecting scopes, areas of malignant tissue too small to beidentified by standard forms of visual inspection have been identifiedin the bronchi and in the urinary bladder.

[0005] Unfortunately, a clinically significant (photosensitizing) amountof porphyrin may persist in the skin for at least two weeks,(occasionally for more than two months) following the intravenousinjection of HpIX, HpD, or a semi-puridied preparation of HpD, such asPhotofrin II. (Photophrin is a registered trademark of Quadra Logics,Inc. Vancouver, British Columbia, Canada.) This means that patients mustavoid exposure to sunlight (either direct, or through window glass) foran inconveniently long period of time post-injection. Understandably,patient compliance often is poor, and accidental phototoxic “sunburn” isa common occurrence in the weeks following a diagnostic or therapeuticinjection of porphyrin. Persistent photosensitivity is the major hazardassociated with this technique, and is the main reason why it is notused more widely.

[0006] The standard treatments for cancer comprise surgery, radiotherapyand chemotherapy. However, other forms of treatment are also known,including photochemotherapy or photodynamic therapy (PDT), based on thediscovery made over 90 years ago that unicellular organisms, i.e.,certain rapidly growing cells (such as cells of the Lower Kingdom, nowreferred to as Protista), treated with certain chemicals will die whenexposed to light. Thus, synthetic porphyrins have been shown in vitro toprotect cells from infections such as parasites, e.g., tyromastigotesand sphaeromastigotes of Tyropanosoma cruzi, J. Parasitol., 75(6) 1989,p. 970-976, and gram positive bacteria, mycoplasma and yeasts, Malik etal. J. Photochemistry and Photobiology, B. Biology 5 281-293 (1990). P.acne is known to, in vitro, produce intracellular protoporphyrin in thepresence of exogenous ALA. Kjeldstad, Conference on Photosensitizationand Photochemotherapy of Cancer, Det Norske Videnskaps-Akademi, Mar.16-17, 1993, Oslo, Norway.

[0007] PDT is currently being used, on an experimental basis, to treatseveral different types of cancer as well as certain non-malignantlesions such as psoriasis. The patient is given a photo-activatable drugthat has some degree of specificity for the tissue being treated. Atissue volume that includes the target tissue is then exposed tophotoactivating light so as to destroy the target tissue while causingonly mild and reversible damage to the other tissues in the sametreatment volume.

[0008] There are two main types of photochemotherapeutic agents inclinical use at present. The first type, methoxypsoralens, are givensystemically. Ultraviolet light is essential to activate them. Localizedexposure of psoralen-containing tissues to ultraviolet light induces alocalized photochemical reaction that causes the drug to bind covalentlyto the DNA of living cells, thus destroying their proliferativepotential. The second type, porphyrins and related photosensitizers, arealso given systemically (by intravenous injection), althoughoccasionally they are given either topically or by intralesionalinjection. They can be activated by visible (red) light. The localizedexposure of porphyrin-containing tissues to such light ordinarily doesnot induce a chemical reaction between cell components and the porphyrinmolecules. Instead, the porphyrins act as catalysts by trapping theenergy of the photoactivating light and then passing it on to moleculesof oxygen, which in turn are raised to an excited state that is capableof oxidizing adjacent molecules or structures. Cell death is not causedprimarily by damage to the DNA, but by damage to essential membranestructures. The goal of photochemotherapy is sometimes cure (mainly forbasal cell carcinomas), but usually the goal is palliation through localcontrol when none of the standard forms of therapy are considered likelyto offer a significant degree of benefit to the patient.

[0009] Methoxypsoralen (PUVA) therapy is used mainly for the treatmentof psoriasis, but sometimes it is also used to treat very superficialcancers that involve the skin (mainly mycosis fungoides). However, thereare two serious problems with such treatments. First, the procedure hasbeen demonstrated in humans to be carcinogenic. Second, the depth atwhich malignant tissue can be killed is limited to a few millimetersbelow the illuminated surface. These problems severely limit theusefulness of the methoxypsoralens for photochemotherapy.

[0010] 5-Amino-4-oxopentanoic acid, also known as 5-aminolevulinic acidand as #-aminolevulinic acid (“ALA”) has been described in the crossreferenced patents and patent applications first set forth in thisspecification for detecting and treating rapidly growing cells. ALA hasalso been reported for use in attenuating the growth and killing plantsand insects when applied directly to such organisms followed by exposureto light, based on work of Rebeiz et al.

[0011] Synthetic porphyrins have also been used as photochemotherapeuticagents in treating rapidly growing, e.g. rapidly dividing or rapidlymetabolizing infectious cells, such as infectious pathogens, includingprotozoal parasites, such as Plasmodium falciparium (which causesmalaria in humans), various other species of Plasmodia, Leishmania, andamoebae, pathogenic fungi, and microplasma, including the variousparasitic forms, all such cells and organisms being referred to hereinas Protista. The term Protista as used here and in the literature refersto the lowest orders of the animal and vegetable kingdoms, single celledor collections of single celled organisms including: the eukaryotes,including protozoa, fungi and algae, and the prokaryotes, which arebacteria and blue-green algae.

[0012] At present, the porphyrins most commonly used forphotochemotherapy are Hematoporphyrin IX (HpIX), Hematoporphyrinderivative (HpD) and various semi-purified preparations of HpD such ascommercially available Photofrin7 II, a semi-purified form of HpD. Whenporphyrins are used as photosensitizers, cell death results from damageto cell membranes. Consequently, malignant transformation is not aserious problem. Moreover, since the visible (red) light that is used tophotoactivate porphyrins penetrates tissue much more deeply than doesthe ultraviolet light that must be used to photoactivatemethoxypsoralens, the depth at which porphyrin-treated tissue can bekilled is substantially greater. Also, since certain types of porphyrinsshow a significant tendency to accumulate preferentially in malignanttissues, it is sometimes possible to destroy malignant tissue withoutcausing clinically significant damage to adjacent normal tissues.

[0013] The main problem with the systemic use of HpIX, HpD and PhotofrinII is that photosensitizing concentrations persist in the skin forseveral weeks to several months following their administration.Consequently, severe accidental phototoxic skin reactions may occurunless the patient avoids exposure to sunlight (either direct, orfiltered through window glass) until the concentration of thephotosensitizer in the skin has been reduced to a harmless level. Atpresent, the problem of photosensitivity following the administration ofporphyrins is handled by advising the patient to avoid any form ofexposure to sunlight (or to very bright artificial lights) for a periodof at least two weeks post-injection, and to initiate subsequentexposure to sunlight very cautiously. Not all patients comply with theseinstructions, since it often is quite inconvenient to do so. Inaddition, the use of a sunscreen with a high blocking factor isrecommended with warning that this will only reduce the hazard somewhat,not eliminate it completely. In a few cases, patients whosephotosensitization persisted for more than a month post-treatment havebeen given large daily doses of beta-carotene over a period of severalmonths in an attempt to prevent accidental phototoxic damage. Finally,attempts have been made to reduce phototoxicity by applying thephotosensitizer topically to a limited area.

[0014] However, another type of problem is encountered if HpIX or HpD isapplied topically in DMSO (dimethylsulfoxide), Azone, or some othervehicle intended to enhance their diffusion through tissue. Theporphyrins tend to become immobilized wherever they happened to be whenthe DMSO or Azone becomes diluted by normal tissue fluids to such anextent that the porphyrins can no longer diffuse through the tissue (oreven remain in solution). Consequently, the topical application ofporphyrins often is associated with a loss of specificity for malignanttissues, and normal tissues near the site of application may developpersistent photosensitization from the localized concentration ofporphyrin.

OBJECT OF INVENTION

[0015] It is an object of the present invention to provide a method forthe detection of certain types of malignant and non-malignant cellsincluding a collection of cells, and tissue abnormalities by inducedfluorescence.

[0016] It is yet another object of this invention to provide aphotodynamic (photosynthesizing) treatment method using an agent whichcan be administered either systemically or topically which is not initself a photosenthesizer but which induces the synthesis oraccumulation or both of protoporphyrin IX (PpIX) and other endogenousporphyrins, their precursors and their photoproducts, in rapidly growingcells, including abnormal cells in otherwise normal tissues, in vivo orin vitro.

[0017] The terms porphyrin(s) and their precursors refer to compoundsproduced in vivo in the synthesis of heme and other endogenouslyproduced photoactivatable compounds including their photoproducts.

SUMMARY OF INVENTION

[0018] This invention is based on the finding that exogenouslyadministered ALA and other precursors of PpIX are metabolized inpatients to PpIX and that PpIX preferentially accumulates in rapidlygrowing cells, as contrasted with less rapidly growing cells. The rapidgrowth is correlated with the metabolic activity, so that thedifferential accumulation is affected by the relative metabolic activitybetween different cells.

[0019] This invention provides a method for detecting in a patient, amalignant or non-malignant lesion or abnormality which is sensitive toPpIX, namely those which preferentially accumulate PpIX, comprisingadministering to said patient an effective amount of a precursor of PpIXin the biosynthetic pathway for heme so as to induce an accumulation ofPpIX in said lesions, and exposing said lesions to light having awavelength within the absorption spectrum of said PpIX, thereby toinduce fluorescence in said lesions.

[0020] Another aspect of this invention is a method for treatingmalignant and non-malignant hyperproliferative lesions of the skin,mucosa, endometrium and urothelium which are sensitive to PpIX in apatient, comprising administering to said patient an effective amount ofa precursor of PpIX in the biosynthetic pathway for heme so as to inducesynthesis or accumulation or both of PpIX or other endogenousporphyrins, their precursors and their photoproducts in said lesions,and exposing said lesions to light having a wavelength within thephotoactivating action spectrum of said PpIX to thereby inducephotoactivation in said lesions.

[0021] Thus, the rapidly growing cells involved can be either malignantor non-malignant hyperproliferative cells. The hyperproliferative cellscan be normal, rapidly growing cells or abnormal cells in otherwisenormal tissue. The abnormal cells in an otherwise normal tissue caninclude abnormal rapidly growing cells endogenous to the patient orabnormal, rapidly growing cells which are exogenous to the patient.These rapidly growing cells that are exogenous to the patient shall, forconvenience, be referred to hereby, depending on the degree ofgenerality, as rapidly growing exogenous cells, rapidly growing Protistacells and rapidly growing parasite cells.

[0022] One aspect of this invention is induction in vivo or in vitro ofthe biosynthesis and selective accumulation of fluorescing orphotosensitizing concentrations of protoporphyrin IX or other endogenousporphyrins such as coproporphyrin I, coproporphyrin III, uroporphyrin I,uroporphyrin III, or fluorescent metalloporphrins such as zincprotoporphyrin IX in Protista and parasites of humans or other animals,by exposing said Protista and endogenous cells under appropriateconditions in vivo or in vitro to an effective concentration of5-aminolevulinic acid or other precursor of said porphryin(s) in thebiosynthetic pathway for heme.

[0023] Still another aspect of this invention is the detection orenumeration of Protista and parasites of humans or other animals, byinducing in vivo or in vitro (ex vivo) the biosynthesis and selectiveaccumulation of fluorescing concentrations of protoporphyrin IX or otherendogenous porphyrin in the parasites as described previously, and thenusing such fluorescence to detect, enumerate, or otherwise quantify saidProtista and parasites.

[0024] Yet another aspect of this invention is the selective killing ofProtista and parasites of humans or other animals in vivo or in vitro,by inducing the biosynthesis and selective accumulation ofphotosensitizing concentrations of protoporphyrin IX or other endogenousporphyrin in the Protista or endogenous cells as described above, andthen exposing the photosensitized parasites to an effective dose oflight of wavelengths lying within the photoactivation spectrum of saidporphyrin(s) or of photosensitizing photoproducts of said porphyrin(s)that may be produced during said exposure.

[0025] By another aspect of this invention there is provided use of acomposition comprising a precursor of protoporphyrin IX in thebiosynthetic pathway for heme for the manufacture of a medicament fortreating malignant and non-malignant tissue abnormalities and lesions.

[0026] In preferred aspects of this invention the preferred precursor ofprotoporphyrin IX is 5-amino-4-oxo-pentanoic acid, otherwise known as5-aminolevulinic acid, and a preferred wavelength of the photoactivatinglight is in the range of 625 to 670 nm, more preferably a red light of625 to 640 nm.

[0027] Other objects, features and advantages of the present inventionwill become apparent from the following detailed description. It shouldbe understood, however, that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

DETAILED DESCRIPTION OF THE DRAWING

[0028]FIG. 1 illustrates the duration of survival of individual micefollowing the injection of spleen cells infected with P. yoelii. Group(1) mice were given spleen cells that had been exposed to ALA in vivo bythen kept in the dark. The average survival of the recipients of thesecells was 15 days. Group (2) mice were given the same number of cellsfrom the same cell suspension afterit had been exposed tophotoactivating light. All of these mice remained in good health for 90days, at which time the experiment was terminated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0029] Protoporphyrin IX (PpIX), a naturally occurring photosensitizer,is the immediate precursor of heme in the heme biosynthetic pathway. Allnucleated cells have at least a minimal capacity to synthesize PpIX,since heme is necessary for the synthesis of various essentialheme-containing enzymes. Certain types of cells and tissues cansynthesize relatively large quantities of PpIX. Under normal conditions,the synthesis of PpIX in such tissues is under such tight feed-backcontrol that the cells produce it at a rate just sufficient to matchtheir need for heme. However, the usual rate-limiting step in theprocess, the synthesis of 5-aminolevulinic acid, can be bypassed by theprovision of exogenous ALA, porphobilinogen, or other precursor of PpIX.Certain tissues and organs will then accumulate such a large excess ofPpIX that they become both fluorescent and photosensitive. At least inthe case of the skin, the PpIX appears to be synthesized in situ. ALA,which is commercially available from Sigma Chemical Company and othersources and which is water soluble, can be administered orally,topically or by injection. The oral and parenteral routes lead to theinduction of clinically useful concentrations of PpIX in certain benignand malignant tissues throughout the body. Only certain types of tissuesynthesize and accumulate clinically useful amounts of PpIX whenprovided with an excess of ALA. By the expression “rapidly growing cell”is meant herein any lesion, abnormal cell or normal cell that exhibitscell growth substantially greater than that of the surrounding tissuesand that preferentially accumulates protoporphyrin IX from exogenousALA. Thus, the cells include rapidly growing cells that are endogenousto the patient and rapidly growing exogenous cells such as Protista andparasite cells. The term “rapidly growing cells” is also used here toinclude living, metabolically active cells as contrasted withmetabolically inactive (dead or dormant) cells such as found in themalarial applications of this invention.

[0030] At the present time, treatment of basal cell, baso-squamous andsquamous cell carcinomas and other lesions of the skin, mucosa(respiratory, digestive, and vaginal), endometrium and urothelium iscontemplated. Sites, which could include lesions or cellularabnormalities, generally are those of epithelial or endothelial originincluding but not limited to those involving (i) skin, circulatorysystem and conjunctiva; (ii) the lining of the mouth, pharynx,esophagus, stomach, intestines and intestinal appendages, rectum, andanal canal; (iii) the lining of the nasal passages, nasal sinuses,nasopharynx, trachea, bronchi, and bronchioles; (iv) the lining of theureters, urinary bladder, and urethra; (v) the lining of the vagina,uterine cervix, and uterus; (vi) the parietal and visceral pleura; (vii)the lining of the peritoneal and pelvic cavities, and the surface of theorgans contained within those cavities; (viii) the dura mater andmeninges; (ix) any tissues or suspensions of body fluids containingabnormal cells, including blood, that can be made accessible tophotoactivating light either in vitro, at time of surgery, in vivothrough the skin via surface irradiation or via an optical fibreinserted through a needle; (x) all exocrine glands and associated ducts,including: mammary glands, sebaceous glands, ceruminous glands, sweatglands, and lacrimal glands; mucus-secreting glands of the digestive,urogenital, and respiratory systems; salivary glands; liver, bile ducts,and gall bladder; pancreas (exocrine component); gastric and intestinalglands; prostate; Cowper's, Bartholin's and similar glands. It is alsocontemplated that cell abnormalities in the gonads (testes and ovaries),thymus, spleen, lymph nodes, bone marrow, lymph and blood would also betreated according to the invention. Tumors of the nervous system orconnective tissues (sarcomas) would also be treated according to thisinvention.

[0031] Treatment of non-malignant lesions such as genital warts andpsoriasis and of endometrial tissues for indications such ascontraception, vaginal bleeding and endometriosis is also contemplated.

[0032] As used herein the term “skin” includes:

[0033] (A) the covering of the external surface of most of the body,commonly termed the skin.

[0034] (B) the covering of the external genitalia:—labia majora, labiaminora, clitoris, and associated structures—glans penis, prepuce, andassociated structures

[0035] (C) the covering of the zone of transition between skin and themucosa of the digestive system:—anal verge—vermillion border of the lips

[0036] (D) the lining of the external auditory meatus, and the coveringof the external surface of the tympanic membrane

[0037] (E) all exocrine glands and associated ducts that are located atleast partially within an epidermal surface described above, or withinthe underlying dermis, such as the pilosebaceous units of the skin.

[0038] The term “mucosa” includes:

[0039] (A) the lining of the whole of the respiratory tract: nasalpassages and nasal sinuses, nasal pharynx and associated structures,larynx, vocal cords, and associated structures, trachea, bronchi, andbronchioles

[0040] (B) the lining of the whole of the digestive tract: oral cavityand tongue, oral pharynx and laryngeal pharynx, esophagus, stomach,small intestine, large intestine, caecum, and appendix, sigmoid colonand rectum anal canal

[0041] (C) the lining of the whole of the urogenital tract: urethra,bladder, and ureters, renal pelvis and renal calyces, vagina, uterinecervix, uterus, and Fallopian tubes, vas deferens, seminal vesicles,ejaculatory duct, ampulla of vas, epididymis, and associated structures

[0042] (D) the conjunctiva and the lining of the tear ducts.

[0043] (E) all exocrine glands and associated ducts that are located atleast partially within one of the mucosal surfaces described above, orwithin the underlying submucosa.

[0044] This invention is especially useful for the treatment of diseasesof Protista and parasitic origin, as defined above, particularly acne,malaria and other parasites or lesions resulting from parasites.

[0045] The term “parasite” includes parasites of humans and otheranimals, including parasitic protozoa (both intracellular andextracellular), parasitic worms (nematodes, trematodes, and cestodes)and parasitic ectoparasites (insects and mites).

[0046] The parasitic Protozoa include: malarial parasites of humans orother animals: malarial parasites of humans, Plasmodium falciparum,Plasmodium ovale, Plasmodium malaria, Plasmodium vivax, leishmanialparasites of humans and or other animals, leishmanial parasites ofhumans, Leishmania tropica, Leishmania major, Leishmania aethiopica,Leishmania brasiliensis, Leishmania guyanensis, Leishmania panamenis,Leishmania peruviana, Leishmania mexicana, Leishmania amazonensis,Leishmania pifanoi, Leishmania garnhami, Leishmania donovani, Leishmaniainfantum, Leishmania chagasi, trypanosomal parasites of humans and/orother animals, trypanosomal parasites of humans, Trypanosoma cruzi,Trypanosoma brucei gambiense, Trypanosoma brucei rhodesiense, amoebicparasites of humans and/or other animals, amoebic parasites of humans,Entamoeba histolytica, Naeglaria species, Acanthamoeba species,Dientamoeba fragilis, miscellaneous protozoan parasites of humans orother animals, miscellaneous protozoan parasites of humans, Toxoplasmagondii, Pneumocystis carinii, Babesia microti, Isospora belli,Cryptosporidium, Cyclospora species, Giardia lamblia, Balantidium coli,Blastocystis hominis, Microsporidia species and Sarcocystis species.

[0047] Some of these miscellaneous protozoa cause self-limiting diseasein normal people, but serious problems in HIV patients:

[0048] parasitic nematodes in humans and/or other animals, parasiticnematodes in humans, filarial nematodes, Wuchereria bancrofti, Brugiamalayi, Brugia timori, Onchocerca volvulus, Loa loa, Tetrapetalonemaperstans, Tetrapetalonema streptocerca, Mansonella ozzardi, Dirofilariaimmitis, Dirofilaria tenuis, Dirofilaria repens, intestinal nematodes,Ascaris lumbricoides (roundworm), Necator americanus (hookworm),Ancylostoma duodenale (hookworm), Strongyloides stercoralis(threadworm), Enterobius vermicularis (pinworm), Trichuris trichiura(whipworm), Trichostrongylus species, Capillaria philippinensis, tissuenematodes, Trichinella spiralis, Anasakis species, Pseudoterranovaspecies, Dracunculus medinensis, parasitic trematodes in humans and/orother animals, parasitic trematodes in humans, Schistosoma mansoni,Schistosoma haematobium, Schistosoma japonicum, Clonorchis sinensis,Paragonimus species, Opisthorchis species, Fasciola hepatica,Metagonimus yokogawai, Heterophyes heterophyes, Fasciolopis buski,parasitic cestodes in humans and/or other animals, parasitic cestodes inhumans, Taenia saginata, Taenia solium, Hymenolepis species,Diphyllobothrium species, Spirometra species and Echinococcus species

[0049] The method of this invention comprises the administration of ALA,other precursors of PpIX and other endogenous porphyrins, to thepatient. The administration can also be in vitro as applied to tissuesof the patient, i.e., ex vivo. In ex vivo methods, tissue containing therapidly growing cells are removed from the patient, an effective amountof ALA or endogenous porphyrin is added thereto, then the preparation issubjected to photoactivating light, before being readministered to thepatient. The amounts of ALA constituting an effective dose can bedetermined by one skilled in the art by analogy with the doses used forsynthetic porphyrins, based on milligrams per kilogram body weight forin vivo systemic application and the typical concentrations for topicalor ex vivo applications. The compound can be conveniently used orally orintravenously at a dosage of about 10 to 100 mg/kg per single dose,preferedly as a dosage of 40-50 mg/kg; however split dosages of 10 mg/kgfour times per day may also be given. The compound can be used topicallyat a dose of between 2% to 100%, with 100% being dry powder. Ex vivoconcentrations of the compound are used on cell suspensions in a rangeof 1-5 mM, with a preferred range of 1-2 mM; however, if serum ispresent, a higher dose of about 15 mM should be used. If ex vivo use onwhole blood, the compound is used at about 15 mM; however, if an ironkelator, such as Desferol® or des ferroxamine, a lower concentration maybe used.

[0050] Thus, one application for the method of this invention is thedetection and quantitation of parasites by ALA-induced fluorescence. Theforegoing includes fluorescence flow cytometry of suspensions of cellsor parasites ex vivo, fluorescence microscopy of cells, including butnot limited to tissues, body fluids, fecal material in vivo or ex vivo,and quantative spectrophotofluorimetry of cells, including but notlimited to tissues, body fluids, urine, or fecal material in vivo or exvivo.

[0051] Another application for the method of this invention is thekilling of parasites preferentially photosensitized by exposure to ALAor an endogenous porphyrin either in vivo or ex vivo. The conjunctiva,which can be treated either topically or systemically with ALA, followedby, after an appropriate period of time, exposure of the skin orconjuctiva to photoactivating light. The parasites can also be presentin the peripheral blood, in which case the ALA can be administeredsystemically, followed by, after an appropriate time, which can beeasily experimentally determined, exposing the defined area of the skinor the blood passing through a large vein to photoactivating light viaan optical guide within a transparent catheter that has been insertedinto the vein. Parasites located within one cm. of the surface of holloworgans that are accessible to fiberscopic examination (respiratorytract, digestive tract, urogenital tract, abdominal cavity, pelviccavity, thoracic cavity) can be diagnosed or treated by systemicadministration of the ALA, followed by, after the appropriate period oftime, exposure of the surface of the target tissue via an appropriatelight guide. Parasites located at sites that are not readily accessibleto fiberscopic examination can be treated with the photoactivating lightvia a light guide that has been surgically introduced into the targetarea through a needle or following surgery.

[0052] Additional applications of the method of this invention are todetect very low levels of metabolically active malarial parasites inperipheral blood or marrow cell suspensions. Such detection can be usedto screen banked blood or as a screening procedure for patientssuspected to have viable malarial parasites. The screening method usingALA would be accomplished by flow cytometry.

[0053] Still another application for the method of this invention wouldbe to distinguish between metabolically active (“viable”) and inactive(“non-viable”) malarial parasites to evaluate the response to therapy inpatients infected with drug-resistant malaria more quickly than is nowpossible. Present methods for quantitating the level of parasitemia donot distinguish between viable and non-viable parasites. Thus, parasitesthat have been killed as a result of recent therapy may not bedistinguishable from viable parasites. If the parasites are in factresistant to the specific drug(s) that are being used for therapy,resistance to these drugs (as shown by failure to reduce the level ofparasitemia) may not become obvious for some time after the initation oftherapy.

[0054] In some cases it might be life-saving to recognize more quicklythat a particular drug is not effective. Since ALA induces fluorescenceonly in plasmodia that are metabolically active, it is possible todistinguish between “viable” and morphologically similar “non-viable”malarial parasites in the peripheral blood. Drugs that fail to produce adecrease in the proportion of the erythrocytes that accumulate PpIXfluorescence when exposed to ALA in vitro could be identified quicklyand replace by other drugs that possibly might be more effective. Thetechnology would not necessarily require flow cytometry, sincerelatively simple and much less expensive fluorometers could be used ifthe level of parasitemia is sufficiently high.

[0055] In cases of partially drug-resistant malaria in which there is aslow response to the drugs, it may be difficult to know when it is safeto discontinue therapy. Since ALA-induced PpIX fluorescence can detectviable plasmodia at very low levels of parasitemia, the technique mightbe used to verify that the parasitemia has been reduced to undetectablelevels before maintenance therapy is discontinued. However, flowcytometry would be required for such low-level measurements.

[0056] The foregoing could also be used to screen in vitro forsensitivity/resistance of the plasmodia from a given patient to selectedanti-malarial drugs, since ALA induces fluorescence only in plasmodiathat are metabolically active.

[0057] Yet another application of this invention is the selectivelphotosensitization and killing of malarial parasites in vivo or in vitroby exposing them to photoactivating light. The light would betransmitted to the malaria parasites in the circulating blood eitherthrough the skin, via an indwelling intravenous or intra-arterialcatheter or by extracorporeal photodynamic therapy of blood, especiallyfor patients who have failed to respond to other therapies, particularlythose who might be considered candidates for a therapeutic exchangetransfusion.

[0058] This invention is also particularly applicable to the treatmentof fungal infections. Fungal infections are becoming of increasingimportance in the past two decades due to the increasing number ofimmunocompromised patients, both by chemotherapy and diseases such asAIDS. Immunosuppression results in an increased incidence of fungalinfections. Fungal infections can be divided into three categories:cutaneous, subcutaneous, and systemic. Cutaneous infections are by farthe most prevalent. Fungal infections predispose their hosts tobacterial superinfections.

[0059] The method of the instant invention is carried out in the samemanner as that for synthetic porphyrins previously reported. Morespecifically, the method of this invention is used to detect or treatrapidly growing cells exogenous to the body, including Protista cellsand parasites.

[0060] The wavelength of the photoactivating light is of someimportance, as it has been shown that between 1 and 10 percent ofincident red light (600-700 nm) can pass through a slab of human tissue1 cm thick, whereas only 0.001 percent or less of blue light (about 400nm) can pass through the same thickness of human tissue. Thephotosensitizer will, therefore, be more successful if it absorbs redlight. PpIX does strongly absorb red light. The present approach hasseveral advantages over the prior art. First endogenous PpIX has a muchshorter half-life in normal tissues (human and mouse, at least) thandoes HpIX, HpD or Photofrin7 II. This greatly reduces the danger ofaccidental phototoxic skin reactions in the days following treatment.Second, the ALA can be applied topically to certain types of lesions.This improves the specificity of the treatment, reduces the danger ofaccidental phototoxic reactions to a very low level, and greatly reducesthe amount of both ALA and PpIX to which the entire body would beexposed if an equally effective dose of ALA were to be givensystemically.

[0061] Both ALA and PpIX are normal products of metabolism, and arehandled quite readily by the biochemical machinery of the body. However,since very large doses of ALA (like large doses of HpIX or HpD) areassociated with a transient decrease in motor nerve conduction velocity,it is desirable to reduce the dose of ALA to the minimum that is stilleffective. Topical application requires much less ALA than systemicadministration. Third, PpIX is rapidly inactivated by thephotoactivating light. Following exposure of tissues containing PpIX toa therapeutic dose of photoactivating light, there is a substantialdecrease in photosensitization of the tissues within the treatmentvolume. Consequently, if PpIX is induced by the topical application ofALA to specific lesions, the patient can be exposed to sunlightimmediately post-treatment without danger of serious phototoxicity.Also, the dosimetry of the photoactivating light is great simplified.Fourth, ALA is an effective inducer of PpIX when given by mouth, bytopical application, or by injection. In contrast, HpIX, HpD andPhotofrin II are effective in most situations only when given byinjection. The versatility of ALA enhances its acceptability for routineuse by the medical profession, since the oral and topical routes ofadministration are much more convenient than the parenteral. Fifth, thenormal and abnormal tissues that can be photosensitized by theadministration of ALA are somewhat different from those that can bephotosensitized by the administration of HpIX, HpD or Photofrin II.Consequently, ALA would be useful in clinical situations in which theother photosensitizers are not.

[0062] Thus the present technique is not merely another way to do whatcan be done already but is, in fact, a significant advance intherapeutic capability.

[0063] Without further elaboration, it is believed that one skilled inthe art can, using the preceding description, utilize the presentinvention to its fullest extent. In carrying out the method of thisinvention, the quantities of materials utilized are not in themselvescritical and can be varied within the scope and spirit of the invention.The following examples are merely illustrative of preferred embodimentsand not intended to be limitative of the remainder of the disclosure inany way whatsoever.

EXAMPLE 1

[0064] Long Term Photodynamic Endometrial Ablation—Rats were dividedinto 2 groups (6 and 7 rats/group) and their uterine horns were injectedwith 4 or 8 mg ALA. Example 1, of U.S. application Ser. No. 08/082,113,filed Jun. 21, 1993 (U.S. Pat. No. 5,422,093), was repeated with theexception that all rats were exposed to light and the time from ALAadministration to breeding was extended from 10-20 days to 60-70 days.All other procedures were identical to Example 1.

[0065] Breeding 60-70 days after photodynamic treatment with 4 mg ALAresulted in no implantations in the uterine horns treated with ALA (n=6)whereas fetuses were found in all control uterine horns treated withsaline (n=6). These results confirmed the long term endometrial ablativeeffect of PDT. In the groups of rats (n=7) treated with 8 mg ALA 2 of 7became pregnant in ALA treated uterine horns compared with 7 of 7pregnancies in the saline treated horns.

[0066] Histology—In order to show normal uterine histology of anonpregnant uterine horn contralateral to a pregnant uterine horn oneuterine horn was ligated at its distal end prior to breeding. Atgestation of 10-15 days nonpregnant uterine horns were harvested andhistologically processed. The uterine mucosa was lined with columnarepithelium and there was hypertrophic infolding of endometrial tissuewith tortuous glands. In contrast, prior photodynamic treatment with ALAconsistently resulted in an atrophic endometrium despite the hormonalstimulus of the contralateral pregnancy.

EXAMPLE 2

[0067] The procedures of Example 1 (U.S. Pat. No. 5,422,093) wererepeated with 1, 2, 3, 4 and 5 hour incubation periods using a level of1 mM of ALA. No significant fluorescence was observed in the myometrialsamples or in the endometrial samples incubated for 2 hours. Maximumfluorescence was observed in the endometrial samples incubated for 4hours.

EXAMPLE 3

[0068] Endometrial Fluorescence in vivo following Topical Application ofALA in the Non-human Primate—50 mg of ALA was injected into the uterinelumen of an adult, healthy, female rhesus monkey following exposure ofthe uterus at laparotomy. A hysterectomy was performed 3 hours later andcross sectional slices incorporating endometrial and myometrial tissuewere taken from the uterine specimen. These slices were subjected toexamination by fluorescence microscopy as in Example 2 and 3 above.Fluorescence was observed throughout the endometrium of all slices. Nofluorescence was observed in the myometrium.

[0069] The above examples clearly illustrate that endometrial ablationin a range of animal species, including humans, by photodynamic therapyusing ALA can be achieved with little or no damage to the underlyingmyometrial tissues.

EXAMPLE 4 Detection or Treatment of Yeast and Fungi

[0070] A. In Vitro Studies—Clinical isolates of Candida albicans,Candida glabrata, and Cryptococcus neoformans and environmental isolatesof Penicillium species, Aspergillus niger, Aspergillus fumigatus, andAlternaria species and Saccharomyces cerivisiae (brewer's yeast)obtained from the clinical microbiology laboratories of Kingston GeneralHospital, Kingston, Ontario, Canada were used. The organisms wereplated, and during rapid growth were treated with various concentrationsof ALA varying from 1 mM to 100 mM by flooding or by using diffusionwells in the agar, while the isolates of Penicillium and Aspergilluswere treated with 40% or 80% solutions of ALA in water and thePenicillium species, Alternaria species, Aspergillus niger andAspergillus fumigatus were treated with 20% ALA in water via diffusionwells. Treatment of the various fungi resulted in fluorescence emissionpeaks that showed the characteristics of PpIX. Positive PpIXaccumulation occurred in both molds and yeasts.

[0071] B. In Vivo Studies—The procedure of Giger et al. Infection andImmunity 19 (2) 499-509 (February 1978) was used with the followingmodifications. A clinical specimen of C. albicans was replated in bloodagar so it was actively growing and left at room temperature for 72hours. The sample was suspended in TSB to McFarland 0.5 turbidity afterwhich a 1.0 ml sample was inoculated into an aerobic culture bottle andleft shaking for 24 hours on a 37° C. rotor shaker. A 10 ml sample waswithdrawn and centrifuged at 70,000 rpm for 10 minutes to separate thecells from the media. The supernate was discarded and the pelletresuspended in 10 ml of TSB. Serial dilusions (10-1 to 10-5) were madein and replicated twice on agar and left to incubate for two days at 37°C. The McFarland 1.0 sample was centrifuged and the pellet resuspendedin 1.0 ml buffer for injection.

[0072] On day zero an intradermal injection of the C. albicanssuspension (about 7×106 organisms/ml saline) was made into the rightflank of 5 adult hairless mice. The amount was just enough to make asmall vesicle under the skin. Lesions form by day 2. Later, some micewere given a second injection on the opposite side.

[0073] Three hours prior to their sacrifice, the mice were given 240mg/kg ALA (10 mg/ml) by intraperitoneal injection, with the exception ofmouse #3 which was used as a control. Fluorescence emission spectra onthe live mice were taken every 15 minutes (mouse #1 readings every 20minutes) for 3 hours after injection on each lesion, and at variouscontrol areas of the mice—neck skin flap and lateral side opposite thelesion on mouse 5. Three hours after the injection of ALA the mice weresacrificed and the lesions were excised. The lesions in mice 1,2,3, and4 were frozen in 2-methylbutane cooled to the temperature of liquidnitrogen. The frozen lesions were sectioned and slides were prepared forspectral analysis or fluorescence microscopy, H and E staining forhistology, and Grocott silver stains for fungi identification.

[0074] Primary and secondary lesions showed increased PpIX accumulationrelative to the control mice.

EXAMPLE 5

[0075] (1) Selective induction of the synthesis and accumulation ofprotoporphyrin IX and/or other endogenous porphyrins within parasites invivo or in vitro.

[0076] In vivo—If the parasites in question involve the skin,conjunctiva, oral mucosa, nasal mucosa, anal mucosa, or urothalium, ALAmay be applied directly to the surface of the affected tissue. If theparasites are located at sites that are not suitable for topicalapplication, an effective amount of ALA is administered systemically,either by mouth, by subcutaneous injection, or by intravenous injection.

[0077] In vitro—The material suspected of containing parasites isincubated under appropriate conditions in the presence of an effectiveconcentration (generally around 5 mM) of ALA.

EXAMPLE 6

[0078] IN VIVO STUDIES—The injection of an effective dose of5-aminolevulinic acid (ALA) into mice infected with P. yoelii leads tothe accumulation of fluorescing and photosensitizing concentrations ofprotoporphyrin within metabolically active parasites. There is no suchaccumulation of protoporphyrin within non-viable parasites, or withinnormal erythrocytes or leukocytes. In parasitized erythrocytes, theprotoporphyrin accumulation is localized to the parasite itself.

[0079] Metabolically active (viable) malarial parasites can bedistinguished readily from parasites that are inactive (dead), sinceonly parasites that are metabolically active can synthesizeprotoporphyrin. In addition, metabolically active (viable) malarialparasites can be killed selectively by exposing infected blood or cellsuspensions to photoactivating wavelengths of light. This procedurecauses no significant damage to the accompanying normal erythrocytes andleukocytes, since they do not accumulate enough protoporphyrin to becomephotosensitized.

EXAMPLE 7

[0080] Demonstration, Quantification, and Analysis of ALA-InducedFluorescence Within Erythrocytes Parasitized by P. yoelii—Normal micewere given intraperitoneal injections of blood or spleen cells obtainedfrom mice infected with P. yoelii. When the malaria was wellestablished, some of the infected mice were given a singleintraperitoneal injection of 250 mg of ALA per kg of body weight.Controls included infected mice that were not given ALA, andnon-infected mice that were given/not given ALA.

[0081] At various intervals thereafter, suspensions of blood and/orspleen cells were examined by the following techniques.

[0082] Fluorescence Microscopy: Red fluorescence developed withinparasitized erythrocytes of mice given ALA, but not within any of thecontrols. This fluorescence was localized to the plasmodia.

[0083] Fluorescence Flow Cytometry: Large numbers of erythrocytes insuspensions of cells from the peripheral blood and spleen of heavilyparasitized mice given ALA developed red fluorescence. Cells from thecontrol mice were uniformly negative. This technique permitted the rapiddetection and enumeration of erythrocytes that containedmetabolically-active parasites, and produced relative values for theintensity of ALA-induced fluorescence in such erythrocytes.

[0084] Spectrophotofluorometry: Blood and spleen cells from heavilyparasitized mice given ALA were washed and pelleted by centrifugation.Protoporphyrin was the only fluorophore that was identified byspectrophoto-fluorometry. As expected, cell pellets from the controlanimals contained only traces of protoporphyrin.

[0085] Demonstration and Quantitation of ALA-Induced Photosensitizationof the Intra-Erythrocytic Stage of P. yoelii.

[0086] Normal mice were given intraperitoneal injections of blood orspleen cells obtained from mice infected with P. yoelii. When themalaria was well established, some of the infected mice were given asingle intraperitoneal injection of 250 mg of ALA per kg of body weight.Controls included infected mice that were not given ALA, andnon-infected mice that were given/not given ALA.

[0087] At various intervals thereafter, suspensions of blood and/orspleen cells were exposed to graded doses of photoactivating light.Light-induced loss of viability of the P. yoelii was demonstrated by (a)loss of infectivity, or (b) loss of ability to accumulate thefluorescent cleavage product of calcein-AM.

[0088] (A) Infectivity Assay: Mice infected with P. yoelii were given astandard dose of ALA by intraperitoneal injection. Peripheral bloodand/or spleen cells were collected after a standard interval, exposed tostandard doses of photoactivating light (including a no-light control)and then injected into normal mice. If the control (no-light) micedeveloped malaria and died while the mice given cells that had beenexposed to a given dose of light remained free of malaria and livedindefinitely, this was considered to be evidence that the light treatedcell suspensions did not contain enough viable plasmodia to cause aninfection.

[0089] For example, a Balb/c mouse with advanced malaria (P. yoelli) wasgiven an intraperitoneal injection of 250 mg of ALA per kg of bodyweight. Four hours later, its spleen cells were suspended in isotonicsaline. Half of the spleen cell suspension was placed on ice andekxposed to photoactivating light (waveband 600-700 nm, intensity 100nW/cm2, total dose 540 J/cm2), while the other half was kept on ice inthe dark. Balb/c mice were injected intraperitoneally with either thelight treated or untreated sample. Survival of the mice was followed for90 days. FIG. 1 illustrates the duration of survival of individual micefollowing the injection of spleen cells infected with P. yoelii.

[0090] (B) Photosensitization studies (Ex vivo studies, directphotoradiation): A group of 4 hairless female mice were used. Two micewere infected with P. yoelii and 2 other mice were non-infected. Miceinfected with malaria were usually in the 8th day following inoculationwith plasmodia. Mice were divided in two groups: one group was treatedwith ALA, the control group was not treated with ALA.

[0091] Both groups were then kept in the dark for a period of 3 hours.Mice were then sacrificed (overdoses of chloroform) and infected bloodcells were obtained from homogenized spleen. Spleens were homogenized in3 cc of isotonic saline solution. From this homogenization 1 cc wastaken and diluted in 24 cc of isotonic saline solution, then from thisdilution 1 cc was taken and placed in test tubes (a total of 8 tubes).Four tubes were kept in dark and four tubes were photoirradiated.

[0092] The source of light was a tungsten lamp with a filter for redlight (600-700 nm). The beam was 10 cm in diameter and the fluence about70 mW/cm2. The samples were placed in ice on a turntable (33 rpm) toassure a uniform distribution of the light in the target cells.

[0093] To determine the viability of the plasmodium after beingirradiated, the contents of each tube were inoculated into hairlessmice, and then the mice were followed for survival.

[0094] Control groups for light alone but not ALA, and ALA but notlight, were also used to make sure that photsensitization was due to ALAplus light.

[0095] (C) Spectrophotofluorimetric studies: A group of 8 hairless 1female mice were used. Four mice were in the 8th day post inoculationwith Plasmodium yoelii with 35% parasitemia and 4 normal mice werenormal (non-infected). The mice were divided into 4 groups of two micein each.

[0096] i) 2 infected mice were given an IP injection of 250 mg/kg of ALAin PBS.

[0097] ii) 2 normal (non-infected) mice were also injected IP with 250mg/kg of ALA in PBS.

[0098] iii) 2 reference controls were included: 2 infected mice withmalaria and 2 non-infected mice, none received ALA.

[0099] All 4 groups were kept at normal room temperature, in the dark,for 4 hours and then sacrificed. Mice were anesthetized with chloroformand then blood was collected by cardiac puncture (heparinized syringewith 20 G 1′ needle). Approximately 0.9 cc blood was collected andtransferred to a 5 cc test tube, kept on ice and in the dark. Test tubeswere then centrifuged for 10 minutes. Using a spectrophotofluorometerset for excitation at 410 nm and fluorescence emission at 635 nm.,fluorescence measurements were taken of the supernant and the pellet.

[0100] Hemolysis with 1% saponin was carried out in samples after thefirst fluorescence measurements, and the free Plasmodia are centrifugedto form a pellet. Then fluorescence measurements were taken from thepellet and the supernant. Protoporphyrin fluorescence was detected onlyin Plasmodial pellet derived from infected mice given ALA.

[0101] (D) Flow cytometer studies (Pharmacokinetic studies): A group of4 hairless female mice were used. Two mice were infected with P. yoeliiand 2 other mice were not infected. Mice infected with malaria wereusually in the 8th day post inoculation with the infected plasmodia. ALAwas given directly to the mice (250 mg/kg intraperitoneal), then 2 dropsof whole blood were withdrawn at regular intervals of time from the tailof each mouse and placed in 5 cc flow cytometer test tubes containing0.5 cc of RPMI 1640 and then analyzed by the flow cytometer to followaccumulation of PpIX. Only infected mice given ALA developedfluorescence in their erythrocytes.

[0102] For the in vitro studies, no ALA was given to the donor mice. Twodrops of whole blood were withdrawn from the tail of each mouse andplaced in a 35 mm petri dish containing 3 cc of RPMI 1640 without phenolred.

[0103] i) a petri dish contained infected whole blood with 5 nM ALA inRPMI.

[0104] ii) a second petri dish contained infected whole blood plus RPMIbut not ALA.

[0105] iii) a third petri dish contained normal whole blood cells with 5mM ALA in RPMI.

[0106] iv) a fourth petri dish contained normal whole blood cells withRPMI but not ALA.

[0107] All petri dishes were incubated at 37 Celsius and room airenvironment. Samples (0.5 cc) were taken at regular intervals from theseincubated petri dishes to be analyzed in the flow cytometer to followaccumulation of PpIX. Only cells from infected mice developed PpIXfluorescence when incubated with ALA.

[0108] Application of ALA-Induced PpIX PDT to the Treatment of Malaria.

[0109] Malaria is caused by infection of the host with unicellularparasites known as plasmodia. At one stage in their life cycle, theplasmodia infect and develop within erythrocytes of the peripheralblood, spleen, and/or marrow. They may infect the liver and certainother organs also.

[0110] Of the numerous species of plasmodia that have been identified,only a few can infect humans. Plasmodia that cause malaria in mice butnot humans provide a safe and convenient model for laboratory studies ofmalaria.

[0111] These examples involve the murine malarial parasites Plasmodiumyoelii (lethal strain) and Plasmodium chabaudi (non-lethal strain) asmodels for human malaria.

[0112] IN VIVO PHOTOSENSITIZATION—When mice infected with the murinemalarial parasites P. yoelii or P. chabaudi were given an adequate doseof 5-Aminolevulinic Acid (ALA) by intraperitoneal injection,

[0113] what appeared spectroscopically to be protoporphyrin (PpIX)accumulated in many of the plasmodia within erythrocytes of theperipheral blood, spleen, and marrow. However, significantconcentrations of PpIX did not accumulate within the non-infectederythrocytes or within the great majority of the leukocytes in theinfected mice.

[0114] a fluorescent material that may have been a complex ofprotoporphyrin with a light metal (perhaps zinc protoporphyrin)sometimes accumulated in association with the PpIX.

[0115] following exposure to an adequate dose of light of wavelengthswithin the photoactivation spectrum of PpIX, the plasmodia that had beenexposed to ALA lost their normal ability to accumulate calcein whenexposed to calcein-AM, and also lost their ability to cause malaria wheninjected into recipient mice. However, the non-infected erythrocytes andthe leukocytes in the same cell suspensions showed no morphologicalevidence of damage following exposure to the photoactivating light.

[0116] IN VITRO PHOTOSENSITIZATION—When peripheral blood, spleen, orbone marrow cells from mice infected with the murine malarial parasitesP. yoelii or P. chabaudi were incubated under suitable conditions in thepresence of an effective concentration of ALA, what appearedspectroscopically to be protoporphyrin (PpIX) accumulated within many ofthe plasmodia in erythrocytes of the peripheral blood, spleen, ormarrow. However, significant concentrations of PpIX did not accumulatewithin the non-infected erythrocytes or within the great majority of theleukocytes in the infected mice.

[0117] The exposure of metabolically active P. yoelii or P. chabaudi toan effective concentration of ALA under suitable conditions in vivo orin vitro leads to the preferential accumulation of fluorescing andphotosensitizing concentrations of PpIX in those plasmodia, but not innon-infected erythrocytes or in the great majority of the leukocytes inperipheral blood, spleen, or bone marrow cell suspensions.

[0118] Plasmodia-specific ALA-induced fluorescence can be used to detectand quantitate metabolically active malarial parasites in suspensions ofcells from peripheral blood, spleen, or marrow.

[0119] Plasmodia-specific ALA-induced photosensitization can be used todestroy malarial parasites selectively, by exposing them in vitro or invivo to an adequate dose of photoactivating light.

EXAMPLE 8

[0120] ACNE—Acne is an inflammatory follicular papular and pustulareruption involving the skin. The treatment of acne using the method ofthe instant invention would be considered to be the treatment of either(a) endogenous lesions of the sebaceous apparatus of the skin due tointrafollicular hyperkeratosis or (b) exogenous bacteria cells presentin the acne lesions, particularly Propionibacterium (Corynebacterium)acne.

[0121] Evaluation of PpIX induced fluorescence in 8 subjects with mildto moderate truncal acne was performed. Bacterial infections arefrequently associated with lesions of acne, e.g., P. acne. Followingevaluation of baseline acne lesion fluorescence, ALA solution 10 and 20%was applied to 10 5 cm² sites on the chest or back of volunteers andevaluated at times 0, 3, 8 and 24 hours after ALA application. One siteof each concentration was also occluded with opaque film for 3 hours andevaluated at similar time points for comparison with unoccluded sites.Fluorescence of both acneiform lesions as well as surrounding normalskin was assessed visually using a 4 point grading system (0=none,4=extremely severe) and documented photographically.

[0122] In all subjects, unoccluded sites had a gradual increase in PpIXfluorescence that was dose dependent, maximum at 8 hours, specific foracne lesions and spared normal surrounding skin. These sites had weak orno fluorescence by 24 hours. Little difference in fluorescence intensitywas noted by lesion type (cornedones vs papules vs pustules) in the samesubject, however, time to maximal fluorescence and maximal fluorescenceintensity was variable from subject to subject. Lesions with surroundingerythema (larger papules and pustules) developed fluorescence extendingto the clinical limit of erythema. Vehicle control sites remained atbaseline. In contrast, occluded sites developed PpIX fluorescence inboth acne lesions and normal surrounding skin that persisted longer thanunoccluded sites and remained present at 24 hours.

EXAMPLE 9

[0123] Cutaneous Fungal Infections—Historically, fungal infections havenot attracted as much attention as bacterial infections. This focus ofresearch has been due to a number of factors, most notably, the highincidence, the degree, and the effect of bacterial infections in humans.However, this trend has changed in the past couple of decades. With theincreasing number of immunocompromised patients, both by iatrogenic(chemotherapy) and disease (AIDS) causes, the incidence of fungalinfections has increased. This has coincided with an increase in themorbidity and mortality rates due to fungal infections in the lastdecade.

[0124] Fungal infections can be divided into three categories:cutaneous, subcutaneous and systemic. While the systemic infections(blastomycosis, candidiasis, etc.) have more serious sequelae, thecutaneous infections are much more prevalent. Between 1971 and 1974,fungal infections had a reported rate of 88/1000 persons in the U.S.with the non-invasive cutaneous infections responsible for 90% of thecases. (This is the number of reported cases. Because of the non-lifethreatening sequelae of cutaneous infections, the actual incident rateis likely much higher.) They were also cited as the most common skininfection.

[0125] Cutaneous infections can be further divided into threesub-categories: superficial, dermatophytoses and dermatomycoses.Superficial infections do not penetrate the outer layer of the skin anddo not involve either the hair or nails. Tinea nigra, black piedra andwhite pedra are examples of superficial fungal infections.Dermatophytoses are infections of the skin, hair, and nails, and includeall layers of the stratum corneum. These infections are caused bydermatophytes, fungi which rarely cause disseminated infections. Theseorganisms release keratinases, which likely explains their localizationwithin the keratinized tissues. These fungi cause little mortality, butare a major cause of morbidity worldwide, and in North America a majorexpenditure of time and money. These infections predispose their hoststo bacterial superinfections. Dermatomycoses are cutaneous infectionscaused by non-dermatophytes and have a greater chance of invasion anddissemination (e.g. superficial candidiasis, mycetoma, sporotrichosis),especially in an immunocompromised host. However, as stated before, thegreater majority of fungal infections are caused by the non-invasivedermatophytes.

[0126] Dermatophytes—Dermatophytes include Trichophyton spp.,Microsporum spp. and Epidermophyton spp. genera. Ecologically, thesefungi are anthrophilic (human to human transmission), zoophilic (animalto human transmission) and geophilic (soil to human transmission,possibly via an animal intermediary). Typically the anthrophilic fungicause little inflammation (increasing the likelihood of chronicinfection) and the zoophilic fungi cause a furuncular reaction.

[0127] Dermatophytoses are named “tinea” followed by the body location(e.g., tinea capitis is an infection of the head). Table 1 lists thedermatophytoses and their causative dermatophyte as found in a survey ofdermatological visits by U.S. Army personnel. This data has beensupported by data collected from surveys of students, inmates, and otherarmed forces personnel in the U.S. The most common dermatophyteworldwide is T. rubrum (survey of major dermatologic centers). TABLE 1Incidence of Dermatophytoses and the Causative DermatophytesDermatophytoses Incidence Most common Dermatophytes (in L to R) tineapedis 44% T. mentagrophytes. T. rubrum tinea unguium 16% T. rubrum, T.mentagrophytes, E. floccosum tinea cruris 15% T. rubrum, T.mentagrophytes, E. floccosum tinea corpis 13% T. Rubrum tinea barbae  4%T. mentagrophytes, T. verrucosum tinea capitis  3% T. tonsurans, M.canis

[0128] Clinical Presentation—These infections are not life threateningbut they can cause a significant amount of discomfort. Typically theycause scaling, fissuring, peeling, itching, burning erythema, and insome circumstances, maceration. Tinea capitis usually causes reversiblehair loss. T. mentagrophytes and T. verrucosum can produce a violentinflammatory reaction. As well, these infections are not pretty and canhave serious aesthetic consequences. The outcome of these infections iseither a spontaneous cure, a cure by medication, a treatable chroniccondition, or a persistent infection despite medication. Both thepresentation and outcome is a function of the dermatophyte virulence andthe host's defense capabilities. Immunocompromised individualsinvariably fare worse than their immunocompetent counterparts.

[0129] Treatment—Dermatophytoses can be treated topically or orally. Theadvantage of treating topically is that more aggressive (toxic) therapycan be employed, whereas orally, less toxic drugs are required. However,topical drugs can cause itching, burning, redness, and sensitization ofthe infected area. Oral therapy has the advantage of gaining access totissue sites normally unattainable to topical therapy (i.e. the nailbeds). To gain access to the site of action, both routes must overcomethe body's natural defenses to foreign molecules since none of the drugsused are endogenous molecules. The imidazoles and triazoles are usedtopically and ketoconazole and griseofulvin orally. However,ketoconazole has a large number of side effects, especially if used fora long period of time, and T. rubrum and T. tonsurans have shownresistance to therapy. Both oral regimens require careful monitoring andsome patients may not be treated because of contraindications.

[0130] Antifungal therapy depends on the thickness of the site infected.Tinea cruris and corpis require a shorter treatment time than tineamanum and tinea pedis because the skin is thinner in the groin and onthe body as compared to the hands and feet. Infections localized to thehair follicle roots require 4 to 6 weeks of treatment (root=3-4 mm underthe skin surface, at 1 mm/week growth). The fingernails require 4-9months of treatment, and the toenails, which grow even slower, require9-18 months of treatment. Due to wearing shoes, the feet and toenailsare also subjected to an environment which is conductive to fungalgrowth (warm, moist), making it more difficult to eliminate theinfection.

[0131]Tinea unguium or onychomycosis has been particularly troublesometo treat. Treatment regimens can last as long as 18 months, withconsiderable time and money invested in the cure. Nail avulsion(removal) is often included in the regimen but may cause considerablepostoperative discomfort. Even so, only a 75-80% cure rate can beobtained with fingernail infections. The results are more bleak fortoenail infections (25% cure rate). If more than one nail is involved, apermanent cure is unlikely. It has been estimated that at least 15-20%of the U.S. population between the ages of 40-60 have onychomycosis.

[0132] Clinical application of ALA-induced photosensitization to chronictoenail infection with dermatophyte (Trichophyton species)An adult malepresented with a chronic dermatophytic infection involving the nail ofthe great toe. The nail itself was badly deformed as a result of theinfection. The surrounding tissues showed evidence of chronic low-gradeinflammation.

[0133] A 20% (w/w) solution of 5-aminolevulinic acid (ALA) in anoil-in-water emulsion (Glaxal Base) was applied to the toenail andsurrounding tissues, and then covered with a water-resistant plasticdressing (Tegaderm). Four hours later, the Tegaderm and residual creamwere removed and the whole area exposed to photactivating (red) light.

[0134] The patient experienced a typical subjective response while thetoe was being exposed to the light—itching, stinging, and a sensation ofmild burning. Upon completion of treatment, the toe was erythematous andsomewhat edematous. This gradually decreased over the next few days.

[0135] Over the next few months, all clinical evidence of the fungalinfection vanished. The toenail is now growing without deformity.

EXAMPLE 10

[0136] The following organisms accumulate fluorescing and/orphotosensitizing concentrations of PpIX when exposed to exogenous ALA:

[0137] (1) Protozoa

[0138] (a) Leishmania—L. donovani[ALA-induced fluorescence]

[0139] (b) Malaria—Plasmodium yoelii[ALA-inducedfluorescence][ALA-induced photosensitization]; Plasmodiumchaubadi[ALA-induced fluorescence][ALA-induced photosensitization]

[0140] (2) Worms

[0141] (a) Nematodes—Lumbricus terrestris (dewworm)[ALA-inducedfluorescence][ALA-induced photosensitization]; Enterobius vermicularis(pinworm)[ALA-induced fluorescence][ALA-induced photosensitization]

[0142]Plasmodium yoelii is a malarial parasite that can infect and growprogressively to produce a lethal form of malaria in susceptible strainsof mice and rats. The inventors have found that, when normal mice areinjected with standard numbers of blood or spleen cells obtained fromdonors infected with P. yoelii, they die of malaria 10 to 20 days aftersuch injection. This mouse model is applicable to the study of malarialinfections in humans, including P. vivax, P. falciparum, P. malariae,and P. ovale.

1. A method for treating in a human patient a non-malignant lesion ofthe esophagus that preferentially accumulates a photoactivatableporphyrin, comprising administering to said human patient in needthereof an effective amount of a precursor of protoporphyrin IX therebyaccumulating therapeutic levels of said protoporphyrin IX, andthereafter exposing said lesion to light capable of photoactivating saidprotoporphyrin IX.
 2. A method for detecting in a human patient anon-malignant lesion of the esophagus that preferentially accumulates aphotoactivatable porphyrin, comprising administering to said humanpatient in need thereof an effective amount of a precursor ofprotoporphyrin IX thereby accumulating therapeutic levels of saidprotoporphyrin IX, and thereafter exposing said lesion to light capableof photoactivating said protoporphyrin IX.
 3. The method of claim 1 or2, wherein said precursor is 5-amino levulinic acid.
 4. The method ofclaim 1 or 2, wherein said wavelength of light is 350-640 nm.
 5. Themethod of claim 1 or 2, wherein said wavelength of light is 600-700 nm.6. The method of claim 1 or 2, wherein said method comprises treating ordetecting the mucosa of the esophagus.
 7. The method of claim 1 or 2,wherein said method comprises treating a premalignant condition in whichthe normal stratified squamous epithelium of the esophagus is replacedby a metaplastic columnar epithelium.
 8. A photosensitizing treatmentmethod for treating non-malignant lesions of the esophagus in a humanpatient comprising (a) administering an agent which is not aphotosensitizer but induces the synthesis of protoporphyrin IX in vivoand then (b) exposing the lesions of the esophagus to a wavelength oflight within the photoactivating spectrum of protoporphyrin IX.
 9. Themethod of claim 8, wherein said agent induces synthesis ofprotoporphyrin IX in the heme biosynthetic pathway.
 10. The method ofclaim 8, wherein said agent is a precursor of protoporphyrin IX.
 11. Themethod of claim 8, wherein said wavelength of light is 350-640 nm. 12.The method of claim 8, wherein said wavelength of light is 600-700 nm.13. The method of claim 8, wherein said agent is 5-amino levulinic acid.14. The method of claim 1 or 8, wherein said agent is administeredtopically.
 15. The method of claim 1 or 8, wherein said agent isadministered systemically.
 16. The method of claim 1 or 8, wherein saidlight is generated from an artificial light source.
 17. The method ofclaim 1 or 8, wherein said light is only within the absorption spectrumof protoporphyrin IX.
 18. The method of claim 1 or 8, wherein saidphotoactivating light is limited to the red and blue regions of thespectrum.
 19. The method of claim 8, wherein said method comprisestreatment of the mucosa of the esophagus.
 20. The method of claim 8,wherein said method comprises treatment of a premalignant condition inwhich the normal stratified squamous epithelium of the esophagus isreplaced by a metaplastic columnar epithelium.